Created by Konrad O'Neill
over 10 years ago
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The nervous system consists mainly of the
1) Brain
2) Spinal Chord
3) Nerve Cells (Neurones)
Stimuli-
is a change such as temperature , light, sound, pressure, pain, movement, touch, chemicals etc
Neurones-
Nerve fibres are made up of lots nerve cells called neurones
Types of Neurones
Relay Neurone-
carry electrical impulses through the spinal cord and up to the brain and from the brain back down along the spinal cord.
Reflexes are fast, automatic protective biological control systems that link a stimulus to a response
Reflex reaction happen without you having to think about them- they are involuntary
What is a synapse?
Describe the Reflex in the finger?
-a stimulus triggers the receptors to send an electrical impulse along the sensory neurone to the relay neurone
-In the spinal cord which is part of the CNS
-Due to a synapse the chemical neurotransmitter diffuses from a high conc to a low conc between the sensor neurone and relay neurone
The eye
Cornea- provides protection for the eye, seals in the aqueous humour. first part that focuses light
Aqueous Humour- helps keep cornea in rounded shape
Iris- controls the amount of light that enters the eye
Retina- light sensitive inner lining of the eye. where images form
Optical Nerve- transmits image seen by retina to brain
Suspensory Ligaments-holds lens in position and changes the focus of the lens
Rods
-Black+White images produced
-Very sensitive to light (works well even at low light)
-Low acuity (resolving power)
-highest conc of rods around edge of retina
-we have more rods than cones
The control of light entering the eye
When the pupil gets smaller the circular muscles contract and the radial muscles relax
When light travels to the eye from a distant object, the rays are almost parallel and need to bent very slightly to be brought back into focus. So when viewing a distant object, the lens must be made thinner and less convex